Panasonic MN103001G/F01K - Manual (Page 399)

I/O Ports
15-33
Fig. 15-7-5 Port 5 Block Diagram (P51)
Internal data bus
TM1IO
P5OUT
P51O
M
P
X
TM1IO/SBI2
P51
P... Represents one bit of each register.
P51I
P5IN
P5DIR
P51D
M
P
X
P51M
P5MD
P51S
P5SS